High brightness diode output methods and devices

ABSTRACT

Devices and methods for maintaining the brightness of laser emitter bar outputs having multiple emitters for coupling and other applications. In some embodiments, at least one brightness enhancement optic may be used in combination with a beam reformatting optic.

RELATED PATENT APPLICATIONS

This patent application is a divisional of U.S. patent application Ser.No. 12/990,215, filed on Jan. 12, 2011, entitled HIGH BRIGHTNESS DIODEOUTPUT METHODS AND DEVICES, naming Edmund L. Wolak, Oscar D. Romero,James Harrison and Sang-Ki Park as inventors, and designated by attorneydocket no. TSI-0302-US, which is a national stage application under 35U.S.C. section 371 of international patent application numberPCT/US2009/043182, filed on May 7, 2009, entitled HIGH BRIGHTNESS DIODEOUTPUT METHODS AND DEVICES, naming Edmund L. Wolak, Oscar D. Romero,James Harrison and Sang-Ki Park as inventors, and designated by attorneydocket no. OCL-0302-PC, which claims the benefit of U.S. ProvisionalPatent Application No. 61/051,628, filed on May 8, 2008 (designated byattorney docket no. OCL-0302-PV), entitled HIGH BRIGHTNESS DIODE OUTPUTMETHODS AND DEVICES, each of which is hereby incorporated by referenceherein, including all text, tables and drawings.

FIELD OF THE INVENTION

Optical systems and components thereof which may be used for maintainingthe brightness of laser emitter bar output beams. Some embodiments maybe useful for high efficiency coupling of laser emitter bar output beamsor other suitable applications.

BACKGROUND

Applications requiring light energy and, in some embodiments, laserenergy, may benefit from the use of solid state light sources such aslaser diodes which are commonly available, reliable to operate andrelatively cost effective as a laser energy source. Such devices mayinclude a plurality of laser emitters in a single bar that emit laserlight simultaneously in a common direction. In addition, multiple solidstate or laser emitter bars may be disposed in a stacked configurationso as to generate even higher power levels.

Laser diode bars are often used for communication technology devices,medical applications and other applications such as militaryapplications where it is desirable to couple the output of all theemitters of a single solid state emitter bar or multiple bars in astacked configuration into a single optical fiber or other opticalconduit. Typically the emitters of such solid state emitter barsgenerate significant amounts of heat during operation and are spacedfrom each other to allow sufficient cooling without the need forelaborate and expensive cooling systems. Such spacing improves thecooling of the bars, but may make coupling of the output beams from themultiple emitters difficult. The coupling of such output beams mayrequire a large number of expensive optical components as well as alarge area for mounting such optics.

In addition, for some applications, beam reformatting optics may be usedin order to further enhance the coupling of the emitter output into adesired device. However, such beam formatting optics may furthercomplicate the coupling process and reduce the brightness of the overalloutput of the bar by generating gaps between output beams of theindividual emitters of a laser emitter bar or bars. One reason for thisis that for some beam reformatting optics the size of the beamlettspassing through the beam reformatting optic must be significantlysmaller than the center to center spacing of a source laser emitter baror the like. As such, brightness may be lost in the downstream optics.

What has been needed are methods and devices for maintaining thebrightness and power of an output of multiple emitters of a laseremitter bar after the output has been reformatted. What has also beenneeded are devices and methods for coupling reformatted output beams ofa laser emitter bar that use fewer optical elements or components.

SUMMARY

Some embodiments of an optical system include a laser emitter bar havingan output with an output axis, a brightness enhancement opticoperatively coupled to the output of the laser emitter bar and a fastaxis collimator disposed between the laser emitter bar and thebrightness enhancement optic and operatively coupled to the output ofthe laser emitter bar. The optical system may also include a beamreformatting optic which is configured to individually rotate outputbeams of emitters of the laser emitter bar and which is disposed betweenthe brightness enhancement optic and the laser emitter bar and coupledthe output of the laser emitter bar.

Some embodiments of a brightness enhancement optic include a facetedtelescope configuration having an input surface with a plurality ofadjacent input facets and an output surface with a plurality of adjacentoutput facets corresponding to each respective input facet. The inputand output surfaces may be substantially parallel to each other and maybe configured to refract substantially parallel input beams through theoptic so as to exit the output facets parallel to each other and spacedcloser together than the spacing of the parallel input beams.

Some embodiments of an optical system include a first laser emitter barhaving a first output with a first output axis, a second later emitterbar having a second output with a second output axis which is orientedsubstantially perpendicular to the first output axis and a brightnessenhancement optic operatively coupled to the first output and secondoutput which is configured to redirect the second output to apropagation direction substantially parallel to the propagationdirection of the first output and interleave the first and secondoutputs. The optical system may also include a first fast axiscollimator disposed between the first laser emitter bar and thebrightness enhancement optic and operatively coupled to the first outputof the first laser emitter bar and a second fast axis collimatordisposed between the second laser emitter bar and the brightnessenhancement optic and operatively coupled to the second output of thesecond laser emitter bar. The system may also include a first beamreformatting optic disposed between the first laser emitter bar and thebrightness enhancement optic and operatively coupled to the first outputof the first laser emitter bar and a second beam reformatting opticdisposed between the first laser emitter bar and the brightnessenhancement optic and operatively coupled to the second output of thesecond laser emitter bar. For some of these embodiments, the brightnessenhancement optic includes a periodic interleaver having an outputsurface with optically transmissive sections alternating with opticallyreflective sections. For such embodiments, each beam of the first outputof the first laser emitter bar may be directed to an opticallytransmissive section and each beam of the second output of the secondlaser emitter bar is reflected by a reflective section in a directionsubstantially parallel to the direction of the first output.

Some embodiments of an integrated optical lens include a lens bodyhaving a first surface and a second surface which together areconfigured to both focus an output of a laser emitter bar andsubstantially collimate an output of a laser emitter bar in a slow axisdirection. For some of these embodiments, the first surface includes anaspheric lens configured to focus an output of a laser emitter bar andthe second surface includes an acylindrical lens configured tosubstantially collimate an output of a laser emitter bar in a slow axisdirection.

Some embodiments of an optical system include a laser emitter bar havingan output with an output axis, a fast axis collimator operativelycoupled to the output of the laser emitter bar and an integrated opticallens comprising a lens body having an first surface and a second surfacewhich together are configured to both focus an output of a laser emitterbar and substantially collimate an output of a laser emitter bar in aslow axis direction. For some of these embodiments, the first surface ofthe integrated optical lens includes an aspheric lens configured tofocus an output of a laser emitter bar and the second surface of theintegrated optical lens includes an acylindrical lens configured tosubstantially collimate an output of a laser emitter bar in a slow axisdirection.

Some embodiments of a method of processing an output of at least onelaser emitter bar includes emitting a plurality of substantiallyparallel beamletts from a plurality of laser emitters, substantiallycollimating the beamletts in a fast axis direction, reformatting thebeamletts by rotation of each beamlett and enhancing the brightness ofthe beamletts by passing the beamletts through a brightness enhancementoptic. Some of these embodiments may also include substantiallycollimating the beamletts in a slow axis direction.

These features of embodiments will become more apparent from thefollowing detailed description when taken in conjunction with theaccompanying exemplary drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment laser emitter bar.

FIG. 2 is a perspective view of an embodiment of a stacked array oflaser emitter bars.

FIG. 3 shows an emission array of the laser emitter bars of the stackedarray embodiment of FIG. 2.

FIG. 4A illustrates an elevation view of an embodiment of an opticalsystem.

FIG. 4B illustrates a top view of the optical system of FIG. 4A.

FIG. 4C is a sectional view of the beams of the emitters of the laseremitter bar of FIGS. 4A and 4B between the fast axis collimator and thebeam reformatting optic.

FIG. 4D is a sectional view of the beams of the emitters of FIGS. 4A and4B between the beam reformatting optic and the brightness enhancementoptic.

FIG. 4E is a sectional view of the beams output of the brightnessenhancement optic in FIGS. 4A and 4B.

FIG. 5 illustrates an embodiment of a reformatting optic.

FIG. 6 illustrates an embodiment of a beam reformatting optic.

FIG. 7A illustrates a top view of an embodiment of a brightnessenhancement optic.

FIG. 7B illustrates a side view of the brightness enhancement optic ofFIG. 7A.

FIG. 8A illustrates a top view of an embodiment of a brightnessenhancement optic.

FIG. 8B illustrates a side view of the brightness enhancement optic ofFIG. 8A.

FIG. 9A shows a top view of an embodiment of an integrated brightnessenhancement optic and slow axis collimator.

FIG. 9B shows a side view of the integrated brightness enhancement opticand slow axis collimator embodiment of FIG. 9A.

FIG. 10A illustrates a top view of an embodiment of a brightnessenhancement optic.

FIG. 10B illustrates a side view of the embodiment of the brightnessenhancement optic of FIG. 10A.

FIG. 11A illustrates a top view of an embodiment of a brightnessenhancement optic.

FIG. 11B illustrates a side view of the embodiment of the brightnessenhancement optic of FIG. 11A.

FIG. 12 is a top view of an embodiment of an optical system embodimenthaving two laser emitter bars and a brightness enhancement optic.

FIG. 13A is a side view of an embodiment of an interleaver brightnessenhancement optic.

FIG. 13B is a top view of the interleaver brightness enhancement opticembodiment of FIG. 13A.

FIG. 13C is a top view of the interleaver brightness enhancement opticembodiment of FIG. 13A showing the optical path of the emitter output ofthe first and second emitter bars through the interleaver brightnessenhancement optic.

FIG. 13D illustrates the optical path of a single emitter output throughthe interleaver brightness enhancement optic of FIG. 13C and theresulting displacement of the optical path.

FIG. 14A is a top view of an embodiment of an interleaver brightnessenhancement optic.

FIG. 14B is a perspective view of the interleaver brightness enhancementoptic of FIG. 14A shown without one prism element and illustrating anembodiment of an interleave surface of the other prism element.

FIG. 14C is a top view of the interleaver brightness enhancement opticof FIG. 14A showing the optical path of the emitter output of the firstand second emitter bars.

FIG. 15A is a top view of an embodiment of an integrated optical lens.

FIG. 15B is a side view of the integrated optical lens embodiment ofFIG. 15A.

FIG. 16A is a top view of an embodiment of an integrated optical lens.

FIG. 16B is a side view of the integrated optical lens embodiment ofFIG. 16A.

DETAILED DESCRIPTION

Embodiments discussed herein are directed to methods and devices forprocessing an output of emitters such as laser emitter bars or chipshaving one or more emitters disposed therein. Embodiments discussedherein are also directed to methods and devices for coupling an outputof laser emitter bars to an optical conduit, such as an optical fiber.Such bars or chips may be mounted to or otherwise incorporated intooptical system embodiments by a variety of methods. For such opticalpackages, it is important that the output array of the chips be properlyaligned, that such alignment may be carried out conveniently andaccurately and that the final configuration dissipate the heat generatedby the chip efficiently. For some embodiments, it may be desirable tominimize the number of optical components used in an optical system inorder to save space and cost of the optical system.

FIG. 1 shows a laser emitter bar 12 having an output surface 14 thatincludes a total of 5 emitters 16 which have optical axes that aresubstantially parallel to each other. Although embodiments discussedherein are generally directed to use with single emitter bars, FIGS. 2and 3 show a stacked array 10 of 4 laser emitter bars 12 that may beused with some embodiments. Each laser emitter bar 12 has an outputsurface 14 that includes a total of 5 emitters 16 disposed adjacent eachother. The emitters 16 of each bar 12 are disposed in a substantiallylinear row along a slow axis direction of the emitters 16, as indicatedby arrow 18. A fast axis direction of the emitters 16 is perpendicularto the slow axis direction 18 and is indicated by arrow 20. The emitters16 are positioned or otherwise configured so as to emit light energy inoutput beams that propagate along an emission axis 22 which may beperpendicular to both the slow axis direction 18 and fast axis direction20. The emission axes 22 of the emitters 16 of the stacked array may besubstantially parallel to each other.

The laser emitter bars 12 are stacked along a fast axis direction 20 ofthe emitters 16 and may be stacked in a periodic and regulardistribution. In the embodiment of FIG. 2, the emitters of a bottomlaser emitter bar 12 are vertically separated from the emitters of anadjacent laser emitter bar 12 by a distance indicated by arrow 24 whichmay be referred to as the pitch of the stacked array 10. For somestacked array embodiments 10, the pitch indicated by arrow 24 may beabout 1 mm to about 3 mm, specifically, about 1.5 mm to about 2.0 mm.Such a stacked array 10 of laser emitter bars 12 and emitters 16 mayallow a large amount of light energy or power to be produced in acompact device for some embodiments.

Laser emitter bar embodiments 12 may have any suitable number ofemitters 16, such as about 1 emitter to about 100 emitters, morespecifically, about 3 emitters to about 12 emitters. For someembodiments, each laser emitter bar 12 having about 5 emitters 16 mayhave an output power of about 5 Watts (W) to about 90 W, morespecifically, about 15 W to about 70 W, and even more specifically,about 20 W to about 30 W. Emitters 16 may include laser diodes such asedge emitting laser diodes, vertical cavity surface emitting lasers(VCSELs) and the like. Materials for the emitters 16 of the laseremitter bar 12 may include semiconductor materials such as GaAs, InP orany other suitable laser gain medium.

Generally, the emitting aperture of a laser diode embodiment of anemitter 16 is rectangular in shape with the long dimension of theemitter 16 having a size of typically tens or hundreds of microns, whilethe short dimension is typically one to several microns in size.Radiation emerging from an emitter 16 diverges with the divergence anglebeing greater along the short emitter 16 direction. Divergence anglesare lower in the direction of the long emitter 16 direction. Someembodiments of the emitters 16 may have a physical width of about 30microns to about 300 microns, more specifically, about 50 microns toabout 200 microns, and the emitters may have a height of about 1 micronto about 3 microns. Some emitter embodiments may have a cavity length ofabout 0.5 mm to about 10 mm, more specifically, about 1 mm to about 7mm, and even more specifically, about 3 mm to about 6 mm. Such emitterembodiments 16 may have a divergence of light energy output of about 2degrees to about 14 degrees, more specifically, about 4 degrees to about12 degrees, in the slow axis direction 18 and a divergence of lightenergy output of about 30 degrees to about 75 degrees in the fast axisdirection 20.

Some embodiments of the laser diode bars 12 may have emitters 16 thatemit light energy having a wavelength of about 700 nm to about 1500 nm,more specifically, about 800 nm to about 1000 nm. Emitters 16 may emitlight having a centroid or peak wavelength of about 300 nm to about 2000nm, more specifically, of about 600 nm to about 1000 nm, includingwavelengths across the near infrared spectrum. Some particularembodiments of useful emitters may emit light at a peak wavelength ofabout 350 nm to about 550 nm, 600 nm to about 1350 nm or about 1450 nmto about 2000 nm. Such laser diode bars may be operated in either apulsed mode or continuous wave mode. Frequently, the output spectralband of individual emitters 16 which are not wavelength controlled (forexample wavelength controlled by providing wavelength-dependent feedbackfrom a volume index grating or the like) may be about 0.5 nm to about2.0 nm or more. Due to the variation in peak emission wavelength inaddition to the spectral band for each individual emitter, the overallbandwidth of the laser emitter bar 12 may be about 2 nm to about 5 nm,for some embodiments. Stacked array 10 includes 4 laser emitter bars 12,however, other embodiments of stacked arrays 10 may have any suitablenumber of laser emitter bars 12. Some stacked array embodiments 10 mayhave about 2 laser emitter bars 12 to about 30 laser emitter bars 12,more specifically, about 2 laser emitter bars 12 to about 10 laseremitter bars 12.

Referring to FIG. 3, stacked array 10 is shown with a fast axiscollimator 26 in the form of a cylindrical lens array disposed over theemitters 16 of the stacked array 10 and configured to substantiallycollimate an output beam of the emitters 16 of each laser emitter bar 12in a fast axis direction 20. Although the embodiment shown in FIG. 3illustrates the fast axis collimator secured directly to the bars 12,the same collimating effect may be achieved with the fast axiscollimator 26 secured apart from and in fixed relation to the bar orbars 12 as will be discussed in more detail below. Fast axis collimator26 may include one cylindrical lens for each laser emitter bar 12 or oneor more monolithic lens arrays as well as any other suitableconfiguration. This fast axis collimation of the emitter output producesan output array 28 as shown wherein the light energy output 30 of eachemitter 16 of each laser emitter bar 12 is substantially collimatedalong the fast axis 20 of the emitters 16 but continues to diverge alongthe slow axis 18 of the emitters 16. The light energy outputs 30 of eachlaser emitter bar 12 may have a substantially rectangular cross sectiontransverse to the direction of propagation and are parallel to eachother so as to produce the output array 28 as shown. The arrangementdiscussed above with regard to the fast axis collimators 26 of thestacked array shown in FIG. 3 may also be used with regard to a singleemitter bar 12.

As discussed above, there remains a needed for methods and devices thatare suitable for maintaining the brightness and power of an output ofmultiple emitters of a laser emitter bar after the output has beenreformatted. There also remains a need for devices and methods suitablefor coupling reformatted output beams of a laser emitter bar that usefewer optical elements or components. FIGS. 4A and 4B show an opticalsystem 30 that includes a laser emitter bar 12 having 5 emitters 16 thatmay emit an output when activated and that has an output axis as shownin FIG. 2 discussed above. A brightness enhancement optic 32 issubstantially aligned with the output axis of the laser emitter bar 12and is positioned and oriented so as to be operatively coupled to theoutput of the laser emitter bar after the emitter output has passedthrough a fast axis collimator 34 disposed adjacent the emitter bar 12and operatively coupled to the output beams thereof. The fast axiscollimator 34 may also be disposed between the laser emitter bar 12 andthe brightness enhancement optic 32. The fast axis collimator serves tosubstantially collimate the emitter output beams of the emitters 16 in afast axis direction. A beam reformatting optic 36 which is configured toindividually rotate output beams of emitters of the laser emitter bar 12about a longitudinal axis of each emitter beam is disposed between thebrightness enhancement optic 32 and the laser emitter bar. For someembodiments, the beam reformatting optic 36 may be positioned betweenthe fast axis collimator 34 and brightness enhancement optic 32 as shownin FIGS. 4A and 4B. The beam reformatting optic 36 is also positionedand oriented so as to be operatively coupled the output of the laseremitter bar 12 that has passed through the fast axis collimator 34.

The brightness enhancement optic 32 is generally configured to maintainor minimize reduction of brightness of the optical system. As such, asused herein, the term brightness enhancement or other similar terms aregenerally directed to the maintenance of brightness or the minimizationof brightness reduction in the optical systems and methods discussedherein. It is understood that the device and method embodimentsdiscussed herein do not increase the level of brightness.

The optical system 30 also includes a slow axis collimator 38 which ispositioned and oriented so as to be operatively coupled the output ofthe laser emitter bar 12 that is emitted from the brightness enhancementoptic 32. The slow axis collimator 38 may be configured to substantiallycollimate an output of the laser emitter bar in a slow axis direction.The slow axis collimator 38 may be disposed between the brightnessenhancement optic 32 and a focusing optic 40. The optional focusingoptics 40 may be disposed after the slow axis collimator 38 and may bepositioned and oriented so as to be operatively coupled to the output ofthe laser emitter bar which is emitted from the slow axis collimator 38.The focusing optic 40 may be configured to focus the output from theslow axis collimator 38 into an optical conduit 41, such as an opticalfiber or the like.

Embodiments of the slow axis collimator 38, focusing optic 40, and fastaxis collimator 34 may have a standard configuration as a cylindricallens, spherical lens, aspherical lens or the like made from any suitableoptical material or materials such as glass, quartz, silica and thelike. For some embodiments, the fast axis collimator 34 may have a widththat is substantially the same as or greater than the width of the laseremitter bar 12.

In operation, the laser emitter bar 12 is activated such that eachemitter 16 of the bar 12 emits an output beam having an optical axissubstantially parallel to output beams of the other emitters 16 of thebar 12. The output beams then pass through the fast axis collimator 34which substantially collimates each of the output beams in a fast axisdirection. A sectional view of an embodiment of output beams emittedfrom the fast axis collimator 34 is shown in FIG. 4C which shows each ofthe 5 output beams having a substantially horizontal orientation that iscollimated in the fast axis direction as indicated by arrow 20 and stilldiverging in the slow axis direction, as indicated by arrow 18. Afterpassing through the fast axis collimator 34, the output beams are thenpassed through the beam reformatting optic 36 which may rotate each ofthe output beams about 85 to about 95 degrees about a longitudinal axisof each output beam and while maintaining the output beams substantiallyparallel to each other. This process effectively switches the fast axisorientation and slow axis orientation of the output beams such that thesection view of the output beams between the beam reformatting optic 36and the brightness enhancement optic 32 may look like the beam sectionsin FIG. 4D for some embodiments.

The beam sections in FIG. 4D have elongated slow axis components due tothe divergence of the output beams in a slow axis direction between thefast axis collimator 34 and the brightness enhancement optic 32. Thebeam sections in the fast axis direction have remained fairly constantrelative to the beam sections of FIG. 4C due to the collimation in thatorientation by the fast axis collimator 34. As can be seen in thesection view of the output beams, there are significant gaps betweenadjacent beams in the fast axis direction due to the narrow profile ofthe beams and due to the combination of the beamlett cross sections andthe de-facto apertures inherent in the beam reformatting optic itself.Specifically, the beamlett cross sections post fast axis collimator 34are typically rectangular in overall geometry, while many of the beamreformatting optics 36 work by reflective or refractive means oftenincluding de-facto apertures at about 45 degree orientations to theprinciple planes of the rectangular shape. Some re-formatting optics 36work by other means (e.g. the Southampton multi-mirror), which stillresult in gaps due to manufacturing issues (coating transitions, shapetransitions for refractive optics etc.). These gaps may then beaddressed by various brightness enhancement optic embodiments 32.

The output beams having the section profile shown in FIG. 4D then passthrough the brightness enhancement optic 32 which expands each of theoutput beams individually in the fast axis direction 20 whilemaintaining the beams parallel to each other and avoiding anyunnecessary introduction of divergence. Some suitable brightnessenhancement optics include telescope optic lens arrays discussed below.

For some embodiments, the telescope lens elements of such an array mayhave the same or similar pitch to the pitch of the laser emitter bar 12.Such telescope lens arrays as well as other optics may expand the outputbeams in a fast axis direction 20 such that the output beam sectionafter the brightness enhancement optic may look like the section view inFIG. 4E. In FIG. 4E, each of the output beams has been expanded by theoperation of the brightness enhancement optic 32 in the fast axisdirection such that the output beams are now adjacent or overlappingeach other in the fast axis direction. The array of output beams thatnow appear more as a single large output beam may then be passed througha slow axis collimating element such as the slow axis collimator 38 andthen focused into the optical conduit 41 which may be an optical fiberof any suitable size and configuration.

For some embodiments, the beam reformatting optic 36 may include anoptical element that serves to rotate each individual beamlett of theoutput of the emitters 16 of the laser emitter bar 12 as discussedabove. FIG. 5 illustrates an embodiment of a refractive beamreformatting optic 42 that includes an array of opposed pairs ofdiagonally oriented cylindrical lenses 44. Each opposed pair of lensesof the beam reformatting optic 42 may have a lateral separation or pitchthat is substantially the same as the lateral separation or pitch of theindividual emitters 16 of the laser emitter bar 12 of the system. Eachlens of an opposed pair of cylindrical lenses may also be set at anangle of about 90 degrees with respect to each other as shown in FIG. 5.The refractive beam reformatting optic 42 may be made from any suitableoptical material such as glass, quartz, silica or the like. For someembodiments, the beam reformatting optic 36 includes a refractive offsetcylindrical lens array for 90 degree beam rotation of each output fromeach emitter element 16 of an emitter bar 12.

Some embodiments of such a refractive offset cylindrical lens array mayinclude diagonally oriented cylindrical lens elements that aresymmetrically disposed on opposing parallel surfaces of a transmissiveblock or substrate that may be made of a refractive solid such as glassor silica. The transmissive block may be sized such that any opposingsymmetrical pair of cylindrical lens elements focus at the same point orline within the body of the transmissive block. Such a configurationwill rotate an incident output beam by approximately 90 degrees, suchthat the fast axis and slow axis of the output beam are reversed. Therotation of individual output beams 16 may be useful to symmetrize thebeam product and beam profile between the fast axis and slow axis andfacilitates subsequent focusing or concentration of the output beamswhile maintaining brightness. The slant or angular orientation of thecylindrical lens elements of the beam reformatting optic may be set toan angle of about 40 degrees to about 50 degrees, as indicated by arrow43 in FIG. 5. Embodiments of refractive offset cylindrical lens arraysfor 90 degree beam rotation, such as beam reformatting optic 42 mayinclude products such as produced by LIMO GmbH, Bookenburgeweg 4-8,Dortmund, Germany.

FIG. 6 shows an embodiment of a reflective or mirror based beamreformatting optic 50 that also serves to rotate each individualbeamlett of the emitters 16 of the laser emitter bar 12 about alongitudinal axis of each beamlett. The reflective beam reformattingoptic 50 includes a plurality of mirror pairs 52 set at 45 degrees to anoptical path 54 of an incident beamlett that generate two sequentialreflections that rotate each beamlett individually about a longitudinalaxis of the output beam and relative to adjacent parallel propagatingbeamlett as shown by arrows 56. The mirrors 52 may be made from a highstrength stable material and may include any suitable highly reflectivecoating or material to enhance reflectance of the surfaces. The amountof rotation about the beamlett axis may vary, but some embodiments mayrotate each beamlett in the same direction and in substantially the sameamount, for example rotation by about 80 degrees to about 100 degrees,more specifically, about 85 degrees to about 95 degrees.

The brightness enhancement optic 32 for the system of FIGS. 4A and 4Bmay include a variety of configurations that serve to maintain thebrightness of an output of the emitters of a laser emitter bar. Someembodiments of brightness enhancement optics 32 may serve to fill ingaps between individual beamletts of the output of emitters of laseremitter bars, particularly after the output has be reformatted by a beamreformatting optic as discussed above. Some embodiments of brightnessenhancement optics 32 serve to expand beamletts of emitters so as tofill in gaps between adjacent beamletts and may also serve to improvethe collimation or reduce divergence of each beamlett. Some embodimentsof brightness enhancement optics 32 may include telescope embodiments oroptics. Some telescope optic embodiments of brightness enhancementoptics may include a cylindrical telescope array having an opposedaligned pair of parallel cylindrical lenses for at least each emitter 16of a laser emitter bar 12 to be used with the brightness enhancementoptic 32. Some embodiments of brightness enhancement optics 32 mayinclude a faceted telescope configuration having pairs of surfaces,including an input surface having a plurality of sequential facets andan output surface having a plurality of corresponding sequential facetsdisposed closer together than the facets of the first surface.

FIGS. 7A and 7B show a brightness enhancement optic 60 that includes acylindrical telescope array of a Keplerian type having a plurality ofopposed aligned pairs of parallel cylindrical lenses 62 disposed with anoptical axis parallel and next to that of each adjacent pair of opposedaligned parallel cylindrical lenses. Each cylindrical lens of theopposed aligned pairs of parallel cylindrical lenses for the embodimentshown is a convex cylindrical lens. The cylindrical lenses are orientedwith the convex portion disposed away from an optic body 64 forming anouter surface of the optic. The focal length and relative spacing of aninput lens and output lens of each opposed pair of lenses may beconfigured to produce an expansion or power of a desired amount whilemaintaining each of the output beams substantially parallel to eachother and without introducing divergence of the beams.

As illustrated by the arrows 66 in FIG. 7A, an incident beamlett fromthe laser emitter bar 12 is expanded laterally in a fast axis direction20 by converging through a focal point due to the lensing of the convexinput lens of the input surface. The input beam then re-expands withinthe optic past the focal point until the beam is re-collimated by thecorresponding output lens which is also convex. The expansion may alsoreduce divergence of the beam an improve collimation so as to enhancethe retention of the brightness. There is no appreciable net impact ondivergence in the slow axis direction due to optic 60. The lenses ofeach side of the optic are substantially parallel to each other and mayhave a spacing or pitch that is substantially the same as the pitch ofthe individual emitters 16 of the laser emitter bar embodiment 12coupled thereto. For some embodiments, the pitch of the lenses 62 may beabout 0.3 mm to about 1.5 mm, more specifically, about 0.4 mm to about1.2 mm. The optic 60 may be made from any suitable optical materialincluding glass, quartz, silica or the like. Outer surfaces of thelenses 62 of the optic 60 may include any suitable anti-reflectivecoating or material in order to enhance transmission of light energythrough the optic. For some embodiments, the power of the telescopeelements of the optic 60 may be about 1.2 power to about 2.4 power, morespecifically, about 1.4 power to about 1.7 power.

FIGS. 8A and 8B show an embodiment of a brightness enhancement optic 70that includes a cylindrical telescope array of a Galilean type that maybe similar in some respects to the Keplerian array of the embodimentshown in FIGS. 7A and 7B and discussed above. As shown in FIGS. 8A and8B, the cylindrical lenses 72 on the input side of the optic 70 areconcave instead of the convex lenses in the input array of lenses onoptic 60 shown in FIGS. 7A and 7B. Once again, the focal length andrelative spacing of an input lens and output lens of each opposed pairof lenses may be configured to produce an expansion or power of adesired amount while maintaining each of the output beams substantiallyparallel to each other and without introducing divergence of the beams.In some cases, the materials, dimensions and features of the enhancementoptic 70 may also be the same as those of the embodiment 60 of FIGS. 7Aand 7B. As shown in FIG. 8A, an incident beam indicated by the parallelarrows is refracted by the input concave lens of the input surface. Therefraction of the input lens causes the beam to diverge within the optic70 as indicated by the arrows within the optic 70. The beam is thenre-collimated by the corresponding output lens on the output surface soas to expand the beam in a fast axis direction while maintaining thedivergence of each output beam. There is no appreciable net impact ondivergence in the slow axis direction due to optic 70.

FIGS. 9A and 9B illustrate an embodiment of a brightness enhancementoptic 80 that may have some of the same features, dimensions andmaterials as those of the optic embodiment 70 of FIGS. 8A and 8B.However, brightness enhancement optic 80 of FIGS. 9A and 9B includes alensing configuration superimposed on an output surface thereof that isconfigured to serve as a slow axis collimator. The slow axis collimatorlensing of the output surface may be used to replace the separate slowaxis collimator optic 38 shown in FIGS. 4A and 4B. In such embodiments,the brightness enhancement optic 80 would take the place of thebrightness enhancement optic 32 and slow axis collimator 38. As shown inFIGS. 8A and 8B, an output surface 82 of the optic 80 includes acylindrical lensing configuration superimposed onto the output lenses 84of the opposed aligned pairs of cylindrical lenses. In thisconfiguration, each of the output lenses of the aligned pairs of lensesis curved in a lens configuration so as to produce convergence in a slowaxis direction. The focal length of the lensing of the output surface 82may be selected to efficiently collimate the output beams of the systemto a desired level. The cylindrical lensing of the output surface 82serves to substantially collimate output of the laser emitter bar 12 ina slow axis direction while the opposed aligned pairs of parallelcylindrical lenses serve to enhance or maintain the brightness of thebeam output by expanding the beams in a fast axis direction as discussedabove with regard to optic embodiment 70. For some embodiments, thefocal length of the lensing of the output surface for slow axiscollimation may be about 5 mm to about 50 mm, more specifically, about10 mm to about 20 mm.

FIGS. 10A and 10B show a brightness enhancement optic 90 having afaceted telescope or plane parallel plate configuration. The facetedconfiguration of the optic 90 has an input surface 92 with a pluralityof adjacent input facets 94 and an output surface 96 with a plurality ofadjacent output facets 98 corresponding to each respective input facet96. The paired input and output facets 94 and 98 may be parallel to eachother and configured to refract substantially parallel input beamsthrough the optic 90 such that the beams exit the output facets parallelto each other so as to maintain the divergence of the input beams. Theoutput beams are spaced closer together than the spacing of the parallelinput beams as shown by the arrows 100 of FIG. 10A. The closer spacingof the adjacent output beams of the emitters 16 may be used to maintainthe brightness of the system for more efficient coupling and otherapplications. For some embodiments, a radius that the input facets 94lie on and a radius that the output facets lie on, in conjunction withthe material of the optic 90 and spacing of the paired facets may beselected to produce a desired amount of compression of adjacent outputbeams. For some embodiments, the optic 90 may be configured such thatincident beams having a fill factor of about 40% to about 80%, may belaterally displaced or otherwise compressed to a fill factor of about80% to about 100%. The fill factor measurement discussed herein refersto the amount of illuminated area within the overall beam profile of allthe output beams. For example, the fill factor of the beam profile shownin FIG. 4D may be about 30% whereas the fill factor in the beam profileor section shown in FIG. 4E may be about 90%. There is no appreciablenet impact on divergence in the slow axis direction due to optic 90.

For some embodiments of optic 90, each corresponding facet pair mayinclude a pair of corresponding cylindrical lenses on the input andoutput facet surfaces of the optic as shown in the embodiment 110 ofFIGS. 11A and 11B. The input surface 112 and output surface 114 of theopposed paired cylindrical lenses 116 and 118 may be substantiallyaligned to each other and configured to refract substantially parallelinput beams through the optic such that the beams exit the output facetsparallel to each other and spaced closer together than the spacing ofthe parallel input beams as shown by the arrows 120 of FIG. 11A. For theembodiment 110 shown, the output beams are neither expanded norcompressed in a fast axis direction 20 as shown by the beams passingthrough the lens pairs of the optic 110, which are configured with apower of about 1. The beams may also be collimated or have reduceddivergence relative to the input beams due to the telescopic effect ofthe paired cylindrical lenses 116 and 118. For some embodiments, thepitch or spacing of the lenses or facets of the input surface may beabout 0.3 mm to about 1.5 mm, more specifically, about 0.4 mm to about1.2 mm. The optic 110 may be made from any suitable optical materialincluding glass, quartz, silica or the like. Outer surfaces of thelenses of the optic may include any suitable anti-reflective coating ormaterial in order to enhance transmission of light energy through theoptic. Although the lens pairs of optic 110 shown have a power of about1, the power of the telescope lens pairs of each facet of the optic 110may have a power of about 0.5 power to about 1.5 power. Also, for someembodiments, a radius that the input lenses 116 lie on and a radius thatthe output lenses 118 lie on, in conjunction with the material of theoptic 90 and spacing of the paired lenses 116 and 118 may be selected toproduce a desired amount of compression of adjacent output beams inconjunction with the expansion or compression due to the lens pairs ofthe optic 110. For some embodiments, the optic 110 may be configuredsuch that incident beams having a fill factor of about 40% to about 80%,may be laterally displaced, compressed and/or expanded to a fill factorof about 80% to about 100%. There is no appreciable net impact ondivergence in the slow axis direction due to optic 110.

For some embodiments, a method of controlling an output of at least onelaser emitter bar 12 using some of the optic embodiments discussedherein, may include emitting a plurality of substantially parallelbeamletts from a plurality of laser emitters 16 of a laser emitter bar.The beamletts may be substantially collimated in a fast axis directionby the fast axis collimator which is operatively coupled to the outputof the laser emitter bar 12. The output beamletts may then bereformatted by a beam reformatting optic 36 which may be configured torotate each beamlett on a longitudinal axis thereof. Each beamlett maybe rotated relative to adjacent beamletts while maintaining the positionof the center or longitudinal axis of the beamlett relative to thecenters or longitudinal axes of adjacent beamletts. The brightness ofthe beamletts overall may be enhanced or otherwise substantiallymaintained by passing the beamletts through a brightness enhancementoptic 32, such as any of the brightness enhancement optics discussedherein. For some embodiments, the output beams may be substantiallycollimated in a slow axis direction by passing the beamletts through theslow axis collimator 38. For some embodiments, the output beams may befocused to a focal spot or pattern suitable for coupling into atransmitting core or the like of an optical conduit 41 by passing thebeamletts through the focusing optics 40. Suitable optical conduits forcoupling of the focused output beam of the laser emitter bar may includeoptical fibers, hollow reflectors, aligned mirror arrays or the like.

Another embodiment of an optical system for managing the output of alaser emitter bar 12 is shown in FIG. 12. The optical system embodiment130 includes a first laser emitter bar 132 having a first output with afirst output axis 134. A second later emitter bar 136 having a secondoutput with a second output axis 138 is positioned such that the secondoutput axis is substantially perpendicular to the first output axis 134.A brightness enhancement optic 140 is positioned and oriented so as tobe operatively coupled to the first output and second output. Thebrightness enhancement optic 140 is configured to redirect the secondoutput to a propagation direction substantially parallel to thepropagation direction of the first output and interleave the first andsecond outputs from the respective first and second laser emitter barsas shown by arrows 142. A first fast axis collimator 144 is disposedbetween the first laser emitter bar 132 and the brightness enhancementoptic 140 and is positioned and oriented so as to be operatively coupledto the first output of the first laser emitter bar 132. A second fastaxis collimator 146 is disposed between the second laser emitter bar 136and the brightness enhancement optic 140 and is positioned and orientedso as to be operatively coupled to the second output of the second laseremitter bar 136. A first beam reformatting optic 148 may be disposedbetween the first laser emitter bar 132 and the brightness enhancementoptic 140 and is positioned and oriented so as to be operatively coupledto the first output of the first laser emitter bar 132. A second beamreformatting optic 150 is disposed between the second laser emitter bar136 and the brightness enhancement optic 140. The second beamreformatting optic 150 is positioned and oriented such that it isoperatively coupled to the second output of the second laser emitter bar136.

For some embodiments, the system 130 includes a slow axis collimator 152which is positioned and oriented so as to be operatively coupled to thefirst and second outputs of the first and second laser emitter bars 132and 136 respectively. For some embodiments, the system includes afocusing optic 154 or optics positioned and oriented to be operativelycoupled to an output of the brightness enhancement optic and configuredto focus the output into an optical conduit 156, such as an opticalfiber or the like. For some embodiments, the brightness enhancementoptic 140 includes a periodic interleaver, as shown in more detail inFIGS. 13A-13D. The periodic interleaver 140 has an input surface 157that may include an anti-reflective coating and an output surface 158with optically transmissive sections 160 alternating with opticallyreflective sections 162. In use, each beam of the first output of thefirst laser emitter bar 132 is directed to an optically transmissivesection of the interleaver and each beam of the second output of thesecond laser emitter bar 136 is reflected by a reflective section in adirection substantially parallel to the direction of the first output asshown by the arrows 142 in FIG. 12.

For some embodiments, the optically transmissive sections 160 andoptically reflective sections 162 of the periodic interleaver 140 areconfigured as parallel stripes of substantially equal width having apitch that may be substantially the same pitch as the pitch of the laseremitter bar emitters multiplied by a factor of about 1.40 to about 1.42,or about the value of the square root of two in order to compensate forthe angular orientation of the incident beams with respect to thesurface of the interleaver 140. For some embodiments, a width of theoptically reflective sections 162 and optically transmissive sections160 may be substantially equal to a length equal to one half the pitchof the alternating sections. For some embodiments, the periodicinterleaver 140 includes a plate 164 having substantially parallelsurfaces which are disposed at an angle of about 45 degrees with respectto the first and second outputs 134 and 138 of the respective first andsecond laser emitter bars 132 and 136. For such embodiments, the path ofthe output beams may be interleaved by the optic 140 as shown in FIG.13C. As shown, the reflected beams from the second emitter bar 136 arereflected from a position disposed between and/or adjacent thetransmitted beams from the first emitter bar 132.

In addition, the thickness of such a plate may cause lateraldisplacement of a beam that passes through the plate from the firstlaser emitter bar as shown in FIG. 13C and indicated by the arrows 141and the symbol Δ (delta). For some embodiments, the first output may belaterally displaced by refraction through the thickness of the plate bya predetermined formula. For some embodiments, the formula for lateraldisplacement is Δ=t×(sin(θ−φ)/cos φ) where sin θ=n sin φ and where t isthe thickness and n is the index of refraction of the interleaver 140.For this relation, θ and φ are the angles relative to the surfaces ofthe interleaver 140 as shown in FIG. 13D.

In addition to the plate embodiment of the periodic interleaver, someembodiments of the periodic interleaver may include a pair of prisms,such as triangular prisms, wherein a periodic interleaver 170 is formedat a surface of the junction between a surfaces of the prisms 172 and174 as shown in the embodiment 176 of FIGS. 14A-14C. For someembodiments, the optically transmissive sections 160 and opticallyreflective sections 162 may be formed on one of the surfaces of thejunction between the two prisms. The sections 160 and 162 formed on oneor more of the surfaces of the prisms 172 and 174 may have the same orsimilar features, dimensions and materials as sections 160 and 162 ofthe periodic interleaver 140 discussed above. It may not be necessary toaccount for the refractive displacement A discussed above as the prismembodiments of interleaver 170 avoid the passage of beams through theparallel plate of 140. The optical path of the beams from the first andsecond bars 132 and 136 and through the optic 170 can be seen in FIG.14C. For such embodiments, the path of the output beams may beinterleaved by the optic 170. As shown, the reflected beams from thesecond emitter bar 136 are reflected from a position disposed betweenand/or adjacent the transmitted beams from the first emitter bar 132.Either optic 140 or 170 may be used with the system 130 shown in FIG.12.

As discussed above, it may be desirable for some embodiments of opticalsystems to minimize the number of optical elements of the system, tominimize the space taken by the optical elements of the system or both.FIGS. 15A and 15B illustrate an integrated optical lens 180 thatincludes a lens body 182 having a first surface 184 and a second surface186 which together are configured to both focus an output of a laseremitter bar and substantially collimate an output of a laser emitter barin a slow axis direction. For some embodiments, the first surface 184may include an aspheric lens 188 configured to focus an output of alaser emitter bar 12 and the second surface 186 may include anacylindrical lens 190 configured to substantially collimate an output ofa laser emitter bar in a slow axis direction. For some embodiments, anacylindrical lens 190 of the second surface 186 may include asubstantially hyperbolic shape. For some embodiments, the first surface184 may include an input surface of the lens body 182 and the secondsurface 186 may include an output surface of the lens body 182. Suchconfigurations may also be modified or reversed with regard to thelensing functions of the input surface 184 and output surface 186 of theintegrated optical lens.

Referring to FIGS. 16A and 16B, an integrated lens 192 is illustratedhaving a lens body 194 and the same or similar features, dimensions andmaterials as those of the embodiment of FIGS. 15A and 15B, with theexception that the first surface 184 includes an output surface of thelens body and the second surface 186 includes an input surface of thelens body. The integrated optics 180 and 192 shown may be substitutedfor the focusing optics and slow axis collimator for any of the opticalsystems discussed above. For any of the integrated optics, the lens bodymay be formed by a molding process, a grinding process, a lithographicetching process or any other suitable process. In addition, theintegrated lens embodiments may be made from any suitable opticalmaterial such as glass, quartz, silica or the like.

Such integrated optics may be incorporated into any of the opticalsystem embodiments discussed herein. For example, an optical system (notshown) may include a laser emitter bar 12 having an output with anoutput axis, a fast axis collimator 34 operatively coupled to the outputof the laser emitter bar 12 and an integrated optical lens 180 includinga lens body 182 having an first surface and a second surface whichtogether are configured to both focus an output of a laser emitter barand substantially collimate an output of a laser emitter bar in a slowaxis direction. For some embodiments, the first surface of the compositeoptical lens may include an aspheric lens configured to focus an outputof a laser emitter bar and the second surface of the integrated opticallens may include an acylindrical lens configured to substantiallycollimate an output of a laser emitter bar in a slow axis direction. Forsome embodiments, the system may further include a brightnessenhancement optic 32 which is operatively coupled to the output of thelaser emitter bar 12 and which is disposed between the fast axiscollimator 34 and the integrated optical lens 180. For some embodiments,the system may further include a beam reformatting optic 36 which isconfigured to individually rotate output beams of emitters of the laseremitter bar 12 and which is disposed between the brightness enhancementoptic 32 and the laser emitter bar 12 and coupled the output of thelaser emitter bar.

With regard to the above detailed description, like reference numeralsused therein refer to like elements that may have the same or similardimensions, materials and configurations. While particular forms ofembodiments have been illustrated and described, it will be apparentthat various modifications can be made without departing from the spiritand scope of the embodiments of the invention. Accordingly, it is notintended that the invention be limited by the forgoing detaileddescription.

What is claimed is:
 1. An optical system, comprising: a first laseremitter bar having a first output with a first output axis; a secondlater emitter bar having a second output with a second output axis whichis oriented substantially perpendicular to the first output axis; abrightness enhancement optic operatively coupled to the first output andsecond output which is configured to redirect the second output to apropagation direction substantially parallel to the propagationdirection of the first output and interleave the first and secondoutputs; a first fast axis collimator disposed between the first laseremitter bar and the brightness enhancement optic and operatively coupledto the first output of the first laser emitter bar; a second fast axiscollimator disposed between the second laser emitter bar and thebrightness enhancement optic and operatively coupled to the secondoutput of the second laser emitter bar; a first beam reformatting opticdisposed between the first laser emitter bar and the brightnessenhancement optic and operatively coupled to the first output of thefirst laser emitter bar; and a second beam reformatting optic disposedbetween the first laser emitter bar and the brightness enhancement opticand operatively coupled to the second output of the second laser emitterbar.
 2. The system of claim 1 further comprising a slow axis collimatoroperatively coupled the first and second outputs of the first and secondlaser emitter bars respectively.
 3. The system of claim 1 furthercomprising focusing optics operatively coupled to an output of thebrightness enhancement optic.
 4. The system of claim 1 wherein thebrightness enhancement optic comprises a periodic interleaver having anoutput surface with optically transmissive sections alternating withoptically reflective sections and wherein each beam of the first outputof the first laser emitter bar is directed to an optically transmissivesection and each beam of the second output of the second laser emitterbar is reflected by a reflective section in a direction substantiallyparallel to the direction of the first output.
 5. The system of claim 4wherein the optically transmissive sections and optically reflectivesections are configured as parallel stripes of substantially equal widthhaving a pitch that is substantially the pitch of the laser emitter baremitters multiplied by about 1.141 and the width of the opticallyreflective and transmissive sections is about one half the pitch of thesections.
 6. The system of claim 4 wherein the periodic interleavercomprises a plate having substantially parallel surfaces which aredisposed at an angle of about 45 degrees with respect to the first andsecond outputs of the respective first and second laser emitter bars. 7.The system of claim 6 wherein the first output is laterally displaced byrefraction through the thickness of the plate.
 8. The system of claim 4wherein the periodic interleaver comprises a pair of prisms wherein theperiodic interleaver is formed on a surface of at least one of theprisms.